KR900001755B1 - Pilot hydraulic system for operating derectional control valve - Google Patents

Abstract

A variable displacement hydraulic pump (14) is driven by an engine (12). A pump regulator (15) controls the displacement volume of the pump. At leaset one actuator (11,17,43,50) is driven by pressurised fluid delivered by the hydraulic pump. The number of engine revolutions can be controlled or altered between different maximum values by altering devices (18,38,41,13,52). The maximum displacement volume can be altered between maximum values. The maximum revolution number and maximum displacement volume altering devices are controlled by the information providers (20, 25,60,36,40,44,54,55). A product of the maximum displacement volume and the number of revolutions becomes at a constant always at the same time when the maximum displacement volume of the pump is varied in response to an output signal of the providers, where a change in the quantity of pumped liquid can be avoided when the maximum displacement volume of the pump is altered.

Description

Hydraulic Construction Machinery Control System

1 is an external view of a wheel type hydraulic excavator of a typical example of a hydraulic construction machine to which the control system of the present invention is applied.

2 is a circuit diagram of a control system according to a first embodiment of the present invention.

3A, 3B, and 3C are schematic diagrams showing the configuration and operation of the rotation speed control means and the maximum rotation speed change means of the embodiment shown in FIG.

4 is a schematic diagram showing the configuration of the extrusion volume control means and the maximum extrusion volume changing means of the embodiment shown in FIG.

FIG. 5 is a flowchart showing a program of control procedures executed by the controller of the embodiment shown in FIG.

FIG. 6 is a characteristic diagram showing the relationship between the engine speed N and the pump discharge amount Q in the embodiment shown in FIG.

FIG. 7 is a diagram showing a P-Q diagram of the hydraulic pump in the embodiment shown in FIG. 2. FIG.

8 is a P-Q diagram of a conventional hydraulic pump of a wheel hydraulic excavator.

FIG. 9 shows the performance curve of the engine in the embodiment shown in FIG.

10 is a flowchart showing a control program in the control system according to the second embodiment of the present invention.

11 is a circuit diagram showing a control system according to a third embodiment of the present invention.

12 is a schematic view showing the configuration of the extrusion volume control means and the maximum extrusion volume changing means of the embodiment shown in FIG.

FIG. 13 is a flowchart showing a program of control procedures executed in the controller of the embodiment shown in FIG.

14 is a characteristic diagram showing the relationship between the engine speed N and the pump discharge amount Q in the embodiment shown in FIG.

15 is a circuit diagram showing a control system according to Embodiment 4 of the present invention.

16 is a circuit diagram showing a control system according to Embodiment 5 of the present invention.

17 is a circuit diagram showing a control system according to a sixth embodiment of the present invention.

FIG. 18 is a flowchart showing a program of control procedures executed in the controller of the embodiment shown in FIG.

19 is a circuit diagram showing a control system according to a seventh embodiment of the present invention.

20A, B, and C are schematic views showing the configuration and operation of the rotation speed control means and the rotation speed change means of the embodiment shown in FIG.

FIG. 21 is a diagram showing the relationship between the operation amount of the engine control lever, the pump discharge amount, and the engine speed in the embodiment shown in FIG. 19; FIG.

FIG. 22 is a characteristic diagram showing the relationship between the engine speed N and the pump discharge amount Q in the embodiment shown in FIG. 19; FIG.

FIG. 23 is a diagram showing a P-Q diagram of the hydraulic pump in the embodiment shown in FIG.

24 is a circuit diagram showing a control system according to Embodiment 8 of the present invention.

FIG. 25 is a flowchart showing a program of control procedures executed in the controller of the embodiment shown in FIG.

Fig. 26 is a flowchart showing a program of control procedures executed by the controller in the control system according to the ninth embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: Wheel (driving wheel) 2: Lower driving body

3: turning wheel 4: upper turning wheel

5, 6, 7: hydraulic cylinder 8: pour

9: arm 10: bucket

11: hydraulic motor 12: engine

13 rotation speed control means 14 variable displacement hydraulic pump

15 regulator 16 control valve unit

17: actuator unit 18: maximum rotational speed variable means

19: means for changing the maximum compression volume 13a: lever

13b: Throttle Lever 13c: Spring

13d: lever 13e: push-pull cable

13f: engine control lever 18a: actuator

18b: solenoid valve 22: pressure source

23: tank 15a: piston

15b: regulator 15c: servo valve

21: controller 20: rotation speed detection means

The present invention relates to a control system of a hydraulic construction machine, and more particularly, to a control system of a hydraulic construction machine having a variable displacement hydraulic pump driven by a prime mover and driven by a hydraulic pump to drive a predetermined desired work element. will be.

One representative of hydraulic construction machinery is a wheel hydraulic excavator, which generally includes a prime mover, an engine, means for controlling the rotational speed of the engine, for example, an engine lever operated in a cab and a governing lever connected thereto. A fuel injection device, at least one variable displacement hydraulic pump driven by the engine, means for controlling the extrusion volume of the hydraulic pump, ie a regulator, and an actuator driven by hydraulic pressure discharged from the hydraulic pump (plural ) And a work element driven by this actuator. The work element is generally a left and right traveling device and other work elements such as a turntable and a front attachment such as a buoy, an arm and a bucket.

In such a hydraulic excavator, by operating a control lever provided for each work element, the direction change valve disposed between the hydraulic pump and the corresponding actuator is switched so that the hydraulic oil from the hydraulic pump driven by the engine corresponds. It is supplied to an actuator to drive it to operate its work element.

As a result, traveling of the traveling device, turning of the swing table, and excavation of the front attachment are performed. However, in the conventional hydraulic excavator, the maximum value of the engine speed generally controlled by the fuel injection device is constant, and the maximum value of the extrusion volume of the hydraulic pump controlled by the regulator, for example, in a swash plate hydraulic pump, The maximum value of the inclination angle of the swash plate is also constant, and these constant maximum rotational speed and maximum extrusion volume are the maximum rotational speed at the maximum extrusion volume, while the hydraulic pump gives the desired maximum discharge amount and at the maximum rotational speed. The pump consumption horsepower is uniquely determined.

In other words, the engine horsepower characteristic is uniquely determined from the setting of the maximum rotational speed in the product of the maximum pump discharge amount in such a hydraulic excavator by the maximum rotational speed and the maximum extrusion volume.

On the other hand, the work element of the hydraulic excavator is to do the same work specified for each work element, such as driving, turning, excavation work, as described above, but the size of the load is greatly changed depending on the amount of work even if the same work element. For example, if you look at the driving device, there is a low load driving to drive a flat road, there is a high load driving to drive a high road, and if you look at the front attachment, there is a heavy excavation work that does a lot of work (work), There is also a digging operation with a relatively small amount of work.

Therefore, in the conventional hydraulic excavator, as described above, the maximum rotational speed of the engine and the maximum extrusion volume of the hydraulic pump are set to be constant, which causes a problem in the case where the work of the load varies greatly.

For example, in a wheel hydraulic excavator, it is not limited to a specific site, general road driving is recognized, and therefore, the maximum speed is often prescribed at a relatively high value. For example, in Japan, the maximum speed is determined to be 35 km / h. Therefore, the wheel hydraulic excavator needs to be able to travel at speeds of up to 35 km / h, and since there are flat roads and hills on general roads, it is possible to drive at a maximum speed of 35 km / h on any road. desirable.

Therefore, the wheel type hydraulic excavator has a special situation that it is desirable to be able to drive at 35 km / h, which is the maximum speed of legal road, even when driving on a path with high load, compared to the caterpillar hydraulic excavator. There was a problem.

In other words, the engine horsepower characteristic of obtaining high pump consumption horsepower by focusing on high-speed high-altitude driving with a heavy load, and setting the maximum rotational speed of the engine and the maximum extrusion volume of the hydraulic pump to obtain a large pump discharge amount It is disadvantageous in terms of fuel and noise when driving on flat roads or excavating operations where the load is light, which is an operation in an area where pump horsepower is less than that of high roads. On the contrary, if the above value is set with emphasis on flat road driving or excavation, it is difficult to obtain a lot of pump power horsepower, and sufficient horsepower cannot be obtained during driving on the hill, and it is possible to drive at a legal maximum speed, for example, 35 km / h. none. In addition to the excavation work on the front attachments, it is a horsepower characteristic to obtain a large pump horsepower by focusing on heavy excavation work, and also set the maximum rotational speed of the engine and the maximum extrusion volume of the hydraulic pump so that the maximum pump discharge amount is appropriate. If you do the heavy excavation work at the desired speed, if you do the light excavation work at the same setting, a part of the engine horsepower will be consumed unnecessarily, the fuel economy will be worse and the noise of the engine will be unnecessarily loud. On the contrary, when the setting is made with emphasis on the light excavation work, sufficient work cannot be performed in the heavy excavation work. This is not only a wheel hydraulic excavator, but also a problem common to crawler hydraulic excavators.

In short, in the case of construction machines such as hydraulic excavators, high load operation is emphasized, and when the maximum rotational speed of the engine and the maximum discharge volume of the hydraulic pump are set, it becomes a problem in terms of fuel efficiency, noise, price, etc. in low load operation. If setting is made with emphasis on the load operation, there is a problem that sufficient performance cannot be obtained in high load operation.

On the other hand, JP-A-58-135341 (JP-A 57-16349), which was published in Japan on August 11, 1983, is provided with a means for detecting the operating state of the actuator, which tends to be subjected to high loads. Is set to a large value when the engine is detected to be in operation, and the engine rotation speed is decreased when the actuator that is prone to light load is reduced and the extrusion volume of the hydraulic pump is reduced. In addition, the present invention discloses a control system for a hydraulic construction machine which increases the extrusion volume of the hydraulic pump, thereby preventing sudden changes in the pump discharge amount due to load fluctuations, conserving energy, and improving operability.

However, as described above, even if the same work element, the amount of work is changed, so the size of the load is changed, and this conventional apparatus cannot cope with such a change in load at all. For example, the problem in the light excavation work in the case where the setting is made with emphasis on the high-speed hillside driving described above cannot be solved at all.

That is, in this conventional apparatus, when the work of which load magnitude changes significantly with respect to the same work element, it has the same fault as the said general hydraulic excavator basically.

Therefore, the inventors of the present application control the hydraulic construction machine that solved the above problem in Japanese Patent Application No. 60-239897 (US Serial No 904118, Korean Patent Application No. 86-7274, India 670 / CAL / 86, EPC 86112330E). The system is proposed.

That is, the control system includes a prime mover, a rotation speed control means for controlling the revolution speed of the prime mover, at least one variable displacement hydraulic pump driven by the prime mover, an extrusion volume control means for controlling the extrusion volume of the hydraulic pump, and A maximum rotation associated with at least one actuator driven by the hydraulic pressure discharged from the hydraulic pump and the rotational speed control means, wherein the maximum rotational speed of the prime mover is changed between at least a first maximum value and a second maximum value greater than that; Regarding the number changing means and the extrusion volume control means, the maximum extrusion volume of the hydraulic pump is dependent on the maximum extrusion volume changing means for changing between at least the first maximum value and the second maximum value larger than that, and the operation mode of the actuator. Means for providing information relating to said maximum rotational speed changing means by means of an output signal from said information providing means; And the maximum extrusion volume changing means, thereby obtaining the maximum rotational speed and the maximum extrusion volume suitable for the operation mode indicated by the output signal. More specifically, as the maximum speed changing means, the maximum speed limiting means for limiting the maximum speed to either the first maximum value or the second maximum value is used, and the information providing means selects the power mode and the economic mode. Mode selector switch is used. When the power mode is selected in this mode selection switch, a combination of the second maximum rotational speed suitable for high load operation and the first extrusion volume maximum is selected. When the economic mode is selected, the first rotation suitable for low load operation is selected. The maximum rotational speed changing means and the maximum extrusion volume changing means are controlled so that the combination of the number maximum and the second extrusion volume maximum is selected.

As a result, sufficient performance can be obtained in both high and low load operations, and troubles such as noise and fuel economy deterioration can be avoided in low load operation. In addition, the product of the first rotational speed maximum and the second extrusion volume maximum and the second rotational speed maximum and the first extrusion volume maximum are set to be substantially equal, whereby the rotational speed of the prime mover is maximized. The discharge amount of the hydraulic pump is not substantially changed even if the combination is changed when at any one of the first and second maximum values declared by the rotation speed limiting means.

However, in the invention of Japanese Patent Application No. 60-239897 (USSerial No, 904118, Korean Patent Application No. 86-7274, India 670 / CAL / 86, EPC 86112330, E), the maximum rotation speed is used as the maximum rotation speed changing means. Since the limiting method is used, when the maximum speed of the prime mover is not limited, when the mode selection switch is operated to change the operation mode, there is a problem that the discharge amount of the hydraulic pump is changed. That is, when the power mode is selected by the mode selection switch, and the actual rotational speed of the prime mover is the rotation speed between the first maximum value and the second maximum value, the mode selection switch is operated to change to the economic mode. The maximum extrusion volume is changed to the second maximum so that the maximum rotational speed is limited to the first maximum. As described above, the product of the first rotational speed maximum and the second extrusion volume maximum is set to be substantially equal to the product of the second rotational speed maximum and the first extrusion volume maximum, but the second maximum rotation It is not equal to the product of the rotational speed smaller than the number and the first extrusion volume maximum. Therefore, the discharge flow rate of the hydraulic pump fluctuates. In any of the mode selections, when the operation of the mode selection switch is instructed when the rotational speed of the prime mover is smaller than the first maximum value, only the maximum extrusion volume is changed, and the rotational speed of the prime mover is not changed at all.

Accordingly, the discharge flow rate of the hydraulic pump is similarly varied. Accordingly, an object of the present invention is to provide a hydraulic construction machine which can freely change the operation mode without incurring inconvenience such as noise and fuel economy, and at the same time, the discharge amount of the hydraulic pump does not substantially change when the operation mode is changed. To provide a control system.

According to the present invention, in order to achieve the above object, a rotation speed control means for controlling the rotation speed of the prime mover and the prime mover, at least one variable displacement hydraulic pump driven by the prime mover, and an extrusion volume for controlling the extrusion volume of the hydraulic pump In relation to the volume control means and the at least one actuator driven by the hydraulic oil discharged from the hydraulic pump and the rotation speed control means, the maximum rotational speed of the prime mover is determined between at least a first maximum value and a second maximum value greater than that. The maximum extrusion volume changing means and the actuator for changing the maximum extrusion volume of the hydraulic pump between at least a first maximum value and a second maximum value larger than the maximum rotation speed changing means and the extrusion volume controlling means. And information providing means for providing information relating to the operation mode, by means of an output signal from the information providing means. A control system of a hydraulic construction machine, which is capable of obtaining a maximum rotational speed and a maximum extrusion volume suitable for an operation mode indicated by the output signal while controlling the competition total number changing means and the maximum extrusion volume changing means, wherein the output of the information providing means The maximum rotational speed changing means and the maximum extrusion volume changing means to change at least the maximum rotational speed of the prime mover so that the product of the maximum extrusion volume and the rotational speed is substantially constant at the same time when changing the maximum extrusion volume of the hydraulic pump in response to a signal. A control system for a hydraulic construction machine is provided, wherein the control means is provided so as to prevent the discharge flow rate of the hydraulic pump from substantially changing when the maximum extrusion volume of the hydraulic pump is changed.

Preferably, the information providing means includes rotation speed detecting means for detecting the rotation speed of the prime mover, and the rotation speed of the prime mover controlled by the rotation speed control means is the first maximum value. The rotational speed is changed again when the rotation speed is exceeded, and the hydraulic pressure is reduced when the rotation speed of the prime mover is at the first maximum value and smaller value in response to the output signal of the rotation speed detection means. The maximum extrusion volume of the pump takes the second maximum value, and if the rotational speed of the prime mover exceeds the first maximum value, the maximum extrusion volume of the hydraulic pump is reduced and the maximum rotational speed of the prime mover is increased. The control system of the hydraulic construction machine configured to control the maximum speed change means and the maximum extrusion volume change means Is provided.

More preferably, the maximum rotation speed changing means may change the rotation speed again by a predetermined amount regardless of the rotation speed of the prime mover controlled by the rotation speed control means so as to obtain a large rotation speed and a small rotation speed. Rotational speed changing means, and the control means responds to the operation mode information from the information providing means, and when the information indicates low load operation, the maximum extrusion volume of the hydraulic pump takes the second maximum value; A first combination in which the rotational speed of the prime mover becomes the smaller rotational speed, and the information indicates a high load operation, the maximum extrusion volume of the hydraulic pump takes the first maximum value, and the rotational speed of the prime mover is the larger rotation; The rotation speed changing means and the maximum extrusion so that the hydraulic pump and the prime mover are controlled by a second combination The control system of hydraulic construction machinery, which consists to control the changing means.

Example 1

FIG. 1 shows a wheel type hydraulic excavator to which a control system according to an embodiment of the present invention is applied, which is a lower traveling body 2 having a traveling wheel (plural) 1 and a lower traveling body ( A buoy 8 and an arm 9 each consisting of an upper swinging body 4 connected via a turning wheel 3 of 2) and driven by hydraulic cylinders 5, 6, and 7 respectively. The front attachment which consists of the bucket 10 is provided. The traveling wheel 1 is driven by a hydraulic motor (see FIG. 2) and the turning wheel 3 is driven by a hydraulic motor (not shown). In addition, below, when these hydraulic cylinders 5, 6, 7 and a hydraulic motor are generically named only an actuator (plural).

The control system assembled to the hydraulic excavator is shown in FIG. 2, which comprises a prime mover, an engine 12 and a rotation speed control means 13 for controlling the rotation speed of the engine 12, and an engine 12. Variable displacement hydraulic pump 14 and extrusion volume control means for controlling the extrusion volume of the hydraulic pump 14, that is, the pump regulator 15, the discharge port of the hydraulic pump 14 has a control valve The actuator unit 17 between the traveling hydraulic motor 11 and the front attachment is connected via the unit 16 and driven by the hydraulic oil discharged from the hydraulic pump 14.

Since the hydraulic pump 14 is a swash plate type pump, controlling the extrusion volume is the same as controlling the tilt angle of the swash plate. Each control valve of the control valve unit 16 is operated by a corresponding operation lever (not shown), and the actuator unit 17 also includes a hydraulic motor for turning in addition to the hydraulic cylinders 5, 6 and 7 of the front attachment. It shall be done. The rotation speed control means 13 includes a maximum rotation speed changing means 18 for changing the maximum rotation speed of the engine 12 between a first maximum value NE and a second maximum value NP larger than that. And the pump regulator 15 has a maximum extrusion volume changing means 19 for changing the maximum extrusion volume of the hydraulic pump 14 between the first maximum value qE and the second maximum value qP larger than that. ) Is installed related.

The maximum values NP, NE, qE, and qP are set to the maximum rotation speed changing means 18 and the maximum extrusion volume changing means 19 such that NE x qE ≒ NP x qP.

The rotation speed control means 13 has a throttle lever connected to a governor (not shown) at the midpoint of the lever 13a, having a lever 13a axially attached to a predetermined portion as shown in FIG. 13b) is connected. A spring 13c is gripped at the tip of the lever 13a, and the other end of the spring 13c is gripped at one end of the lever 13d held in a predetermined portion.

The other end of the lever 13d is connected to the engine control lever 13f in the driver's seat by, for example, a push-pull cable 13e. By operating the engine control lever 13f, the engine speed can be continuously controlled from the idle to the NE in the area below the engine speed NE which is the first maximum value.

Here, the first maximum value NE of the engine speed is the tilt angle of the pump 14, that is, the minimum horsepower required when the extrusion volume is qE so that 35 km / h is obtained when driving on the flat road, or the excavation operation is performed at a desired speed. NE and qE are the maximum rotational speed and the maximum extrusion volume suitable for low load operation.

The maximum extrusion volume changing means 18 has an actuator 18a for controlling the rotation angle of the lever 13a, and in the region where the engine rotation speed exceeds NE, the lever 13a is maximized by the actuator 18a as shown in 3c. By controlling the rotation angle, the engine speed can be rotated to the second maximum value NP.

Here, the second maximum value NP of the engine speed is determined so that 35 km / h can be obtained when driving on a hill at a desired gradient with the minimum required horsepower when the pump tilt angle or the extrusion volume is qP. The maximum rotation speed and maximum extrusion volume suitable for high load.

3A shows the engine idle state in FIG. 3A, the engine speed in FIG. 3B controlled by the engine control lever 13f at the predetermined value NE, and FIG. 3C shows the state of the fold throttle.

In this embodiment, when the engine control lever 13f is pulled to the maximum, the maximum engine speed becomes a value NE 'exceeding NE and the engine control lever 13f does not move even when the actuator 18a is driven. It is supposed to be.

As shown in FIG. 2, the actuator 18a is connected to the pressure source 22 and the tank 23 via the solenoid valve 18b.

As shown in FIG. 4, the pump regulator 15 is connected to an actuator 15b including a piston 15a connected to the swash plate of the hydraulic pump 14 via a link mechanism, and at the same time, the actuator ( The servo valve 15C etc. which selectively connect 15b) with the said hydraulic source 22 and the tank 23 are provided. The maximum extrusion volume changing means 16 includes an actuator 19b having a piston 19a which is abuttable to the piston 15a of the actuator 15b in the pump regulator 15, and the actuator 19b is a hydraulic source. The solenoid valve 19c which selectively communicates with the 22 and the tank 23 is provided.

Referring again to FIG. 2, reference numeral 21 denotes a controller composed of, for example, a microcomputer (MPU), the input port of which constitutes a means for providing information on an operation mode of an actuator installed around an output shaft of an engine. The engine speed sensor 20 is connected. The solenoid valve 18b and the solenoid valve 19c are connected to the output port of the controller 21. When the solenoid valves 18b and 19c have the engine speed controlled according to the program of FIG. 5 described later, below the first maximum value NE, the two solenoid valves 18b and 19c are turned off and the engine speed is rotated. When the first maximum value NE is exceeded, the two solenoid valves 18b and 19c are turned on.

Next, a program stored in the ROM of the controller 21 in advance will be described with reference to FIG. First, the engine speed No is read into the step S1 based on the signal from the engine speed sensor 20. Proceeding to the step S ₂ , the magnitude of the engine speed No read in and the first maximum value NE of the engine speed stored in the ROM are determined in advance. If the signal from the sensor 20 indicating the current engine speed No indicates that the speed NE suitable for low load operation is exceeded, the process proceeds to step S ₃ and indicates that the signal is higher than NE. Proceed to step S4. Staff (S ₃₎ in the ON and the solenoid-operated valve (18b, 19c) with, the staff (S4) is in the OFF with the electromagnetic valve (18b, 19c).

In this way, the maximum rotation speed changing means 18 is configured to change the rotation speed again when the rotation speed of the engine 12 controlled by the rotation speed control means 13 exceeds the first maximum value NE. The controller 21 responds to the output signal of the rotation speed detecting means 20, so that when the rotation speed of the engine 12 is equal to or smaller than the first maximum value NE, the maximum extrusion volume of the hydraulic pump 14 is reduced. Means for changing the maximum rotational speed so as to reduce the maximum extrusion volume of the hydraulic pump and increase the maximum rotational speed of the engine 12 when the maximum value qE of 2 and the rotational speed of the engine 12 exceed the first maximum value; 18 and the maximum extrusion volume changing means 19 are controlled.

In particular, in this embodiment, the controller 21, the maximum rotational speed changing means 18 and the maximum extrusion volume changing means 19 are discontinuous when the rotational speed of the engine 12 exceeds the first maximum value NE. The maximum extrusion volume 14) is changed to the first maximum value NE, and at the same time, the maximum rotational speed of the engine 12 is changed to the second maximum value qE.

The operation of this embodiment configured as described above will be described.

(1) When the engine speed is less than or equal to the first maximum value NE suitable for low load operation When the engine speed is less than or equal to the first maximum value NE suitable for low load operation, both the solenoid valves 18b and 19c are turned off. Therefore, neither the pump maximum tilt angle control actuator 19a nor the engine speed control actuator 18a are biased. Therefore, the maximum extrusion volume of the pump 14 is set to the second maximum value qE suitable for the low load operation and the engine speed is a value corresponding to the operation amount of the engine control lever 13f of the driver's seat. In this case, the N-Q curve is shown by the solid line in FIG. 6, and when the engine speed is NE, the P-Q curve is shown by the dashed-dotted line E in FIG. 8 shows an example of a P-Q diagram in a conventional hydraulic pump that does not perform switching control of the maximum tilt angle as in the present invention. In the conventional example, when the engine speed is lowered to No-No ', the pump discharge amount is also lowered to Qo-Qo', and fuel efficiency cannot be improved while maintaining the working speed.

(2) When the engine speed exceeds the first maximum value NE suitable for low load operation, pulling the engine control lever 13f to the maximum, the solenoid valve when the engine speed reaches NE 'exceeding NE. Both 18b and 19c are turned on, and both the actuator 18a and the actuator 19a are biased. Therefore, the maximum extrusion volume of the pump 14 is set to the first maximum value qP (<qE) suitable for high load operation and the engine speed is the second maximum value NP suitable for high load operation as shown in FIG. 3C. That is, it is controlled by the highest rotation speed of the onboard engine. The state in the N-Q curve in this case is represented by the point P in FIG. 6, and the P-Q curve is as shown by the solid line P in FIG.

Here, the maximum extrusion volume (qE, qP) and the maximum engine speed (NE, NP) are as described above. The maximum engine speed (NE, NP) is qE × NE ≒ qP × NP, where qE> qP, NE < Since it is determined to be NP, in the maximum engine speed and maximum extrusion volume switching, the discharge amount of the pump is kept substantially constant.

Thus, according to this embodiment, for example, when the wheel-type hydraulic excavator starts to climb the path and the throttle lever is opened and the rotation speed exceeds the first maximum value NE, the engine 18a rotates at high speed by the actuator 18a. At the same time as the rotation speed becomes the second maximum value NP, the pump maximum tilt angle becomes smaller than the second maximum value qE when the rotation speed NE is less than or equal to the first maximum value qP. As a result, the engine output horsepower and the pump absorption horsepower are at their maximum, and the wheel hydraulic excavator can ascend while maintaining the desired speed, for example, 35 km / h. On the contrary, when the engine speed is less than or equal to NE, the maximum extrusion volume is set to qE, and as a result, the pump absorption horsepower suitable for low load operation such as a flat road or low excavation can be operated, so that the engine can be operated in a region with favorable fuel consumption rate. In addition, since the engine speed can be driven at NE or lower, the noise is naturally small.

This will now be described again with reference to the engine characteristic curve shown in FIG. In this figure, A ₁ represents an engine speed-engine horsepower characteristic line corresponding to the rotational speed NP suitable for uphill driving, which is a high load operation, and A ₂ corresponds to the rotational speed NE ₁ suitable for flat road driving, which is one of low load operation. corresponding to the engine revolution number-engine horsepower characteristic indicates a line, a ₃ is the engine speed corresponding to the rotational speed NE ₂ suitable for the other of drilling operations of the low load operation - it indicates the engine horsepower characteristic line. B ₁ represents an engine speed-engine torque characteristic line corresponding to the rotational speed NP suitable for uphill driving, which is a high load operation, and B ₂ represents an engine rotation corresponding to the rotational speed NE ₁ , suitable for driving in a flat road, which is one of low load driving. number - indicates the engine torque characteristic line, B ₂ is the engine speed corresponding to the rotational speed NE ₂ suitable for the other of drilling operations of the low load operation - shows the engine torque characteristic line. C ₁ represents the fuel consumption rate characteristic line corresponding to the rotational speed NP suitable for the uphill driving NP which is a high load operation, and C ₂ corresponds to the rotational speed NE ₁ suitable for the flat road driving which is one of the low load operation. The fuel consumption rate characteristic line is shown, and C ₃ represents the fuel consumption rate characteristic corresponding to the rotational speed NE ₂ suitable for the excavation work which is another one of the low load operation. In addition, PS ₁ indicates horsepower required during uphill driving, which is a high load operation, PS ₂ indicates horsepower required for driving on a flat road, which is one of low load driving, and PS ₃ horsepower required during excavation work, which is one of low load driving. Indicates.

As can be seen from this figure, when the first maximum value NE of the engine speed is set to NE ₁ , the engine speed-engine horsepower characteristic line as A ₂ is obtained, and the fuel consumption rate is equal to C ₂ . Therefore, the fuel consumption rate when driving on the flat road with the required horsepower PS ₂ becomes g ₂ . On the other hand, when the same operation is performed with the maximum rotational speed set at NP, the rotational speed increases to N ₂ and the fuel consumption rate is q ₂ . Therefore, the fuel consumption rate is improved from g ₂ to g ' ₂ , and the engine speed is also reduced from N ₂ to NE ₁ , thereby improving noise. Similarly, in the case of excavation work with the first maximum value NE of the engine speed set to NE ₂ , the fuel consumption rate is improved from g ₃ to g ' ₃ , and the engine speed is also reduced from N ₃ to NE ₂ to improve noise. do.

In addition, as shown in FIG. 7, each value is set so that the pump maximum discharge amount QE at engine speed NE and the pump maximum discharge amount QP at engine speed NP are approximately equal, so that the maximum extrusion volume at the time of travel is determined from pE. Since the running speed does not change even when switched to qP, the driving speed is also preferable.

In addition, since the operation mode is changed only when the engine speed exceeds or becomes smaller than the first maximum value NE, there is no inconvenience in that the discharge amount of the hydraulic pump changes according to the change of the operation mode. .

Example 2

Next, a second embodiment of the present invention will be described with reference to FIGS. 2 and 10. FIG. In the first embodiment, when the engine speed is determined based on the signal from the rotation speed sensor 20 and it is determined that the rotation speed exceeds NE, the maximum extrusion volume of the hydraulic pump is increased from qE to qP. Although the engine speed was changed from NE to NP, in this embodiment, a mode selection switch is provided to perform the same control as described above under two conditions with the switching position of the engine speed mode selection switch.

That is, the economic mode for low load operation and the power mode for heavy load operation are set, and either mode is selected by the mode selection switch 25 shown in the dashed-dotted line in FIG. This mode selection switch 33 outputs a power mode signal when operated to the power mode selection position P, and outputs an economy mode signal when operated to the economic mode selection position E. FIG. Thus, the pump maximum tilt angle and engine control are performed in accordance with the processing procedure shown in FIG. 10 instead of the processing procedure shown in FIG. That is, in the step S12, the pump maximum extrusion volume is determined only by the detection signal indicating the engine speed No and the mode signal, the engine speed exceeding the first maximum value NE and only when the power mode is selected. Is changed from qE to qP and power mode operation is performed by changing the maximum engine speed to NP. Under other conditions, the pump maximum extrusion volume is maintained at qE, and the engine speed is controlled in accordance with the operation amount of the engine control lever 25e. According to such a structure, since the economic mode is selected, it is impossible to operate in the power mode, that is, the engine speed NP and the pump maximum extrusion volume qP by mistake, at the time of low load operation.

In the above, the high-speed driving is taken as an example of high load operation, and the low-speed driving or excavation operation is described as an example of the low load operation. However, the present invention is not limited thereto. It is also possible to apply the present invention to such a change in the operation mode with low load operation.

The embodiment of the present invention has been described above with respect to the wheel hydraulic excavator, but the present invention can also be applied to a caterpillar hydraulic excavator. In this case, in particular, the present invention is effective to change the operation mode for the heavy excavation work and the light excavation work.

Incidentally, in the above description, the engine speed is determined in accordance with the program in the controller 21, but may be determined using a comparator or the like without depending on the program. In addition, instead of the rotation speed sensor 20, it rotates by the switch which switches when the engine control lever 13f in a driver's seat or the throttle lever on the engine side moves to the position exceeding the 1st maximum value NE of engine speed. The engine speed may be determined indirectly by the number detecting means. The engine speed is increased by the hydraulic cylinder 18a, but may be performed by an electronic actuator. The maximum tilt angle may also be controlled by an electronic actuator. In this case, the electronic actuator may be driven directly by the output signal of the rotation speed sensor 20.

Although the possibility of the change regarding the specific structure of the Example demonstrated above was not specified, it is applied also to all other Example demonstrated now.

[Examples 3 to 6]

Next, another embodiment (plural) of the present invention will be described with reference to FIGS. 11 to 18. FIG. In the drawings, the same members are denoted by the same reference numerals among the embodiments (multiple) and other embodiments shown in FIGS. 11 to 18, the control means 39, 42, 47, the maximum speed change means 38, 41, 13 and the maximum extrusion volume change means 37 When the rotation speed exceeds the first maximum value NE, the maximum extrusion volume of the hydraulic pump 14 is continuously changed to the first maximum value qP, and the maximum rotation speed of the engine 12 is changed to the second maximum value ( It differs from the above-mentioned embodiment in that it is comprised so that it may change to NP) and is mutually related.

Example 3

First, with reference to FIGS. 11 through 14, a third embodiment of the present invention will be described. In the control system of this embodiment, the variable displacement hydraulic pump 14 is connected to the traveling motor 11 via the control valve 30, and the fixed displacement hydraulic pump 31 is a traveling pedal constituting the traveling operation means. The pilot valve 33 operated by 32 and the switching valve 35 operated by the forward and backward lever 34 are connected to pilot ports 30a and 30b of the control valve 30. A throttle 36 is provided between the fixed displacement hydraulic pump 31 and the pilot valve 33, and the front and rear pressure of the throttle 36 passes through the solenoid valve 37b to change the maximum extrusion volume 37. Actuator 37a can be supplied to (see FIG. 12).

On the other hand, the pressure of the input port on the forward traveling side of the traveling motor 11 is supplied to the actuator 38a of the maximum speed change means 38 of the engine via the solenoid valve 38b connected to the pipeline 60. It is supposed to be. The actuator 38a of this engine maximum speed change means 38 is arranged in association with the speed control means 13 to control the rotation angle of the lever 13a as shown in FIG. 3 above. As shown in FIG. 11, the spring 38c is arrange | positioned in 38a, and by this, in the area | region in which the engine speed exceeds NE, the forward side port of the traveling hydraulic motor 11 is carried out by the actuator 38a. It is configured to increase the engine speed according to the pressure. The pump regulator 15 has the same structure as that of the first embodiment shown in FIG. 4 as shown in FIG.

The maximum extrusion volume control means 37 has an actuator 37a which has a piston 37c which can abut the piston 15a of the actuator 15b in the pump regulator 15, and has a spring 37d disposed therein. In addition, the pressure oil with the pressure difference before and after the throttle 36b is introduced into this actuator 37a via the solenoid valve 37b.

NE)이면 스탭(S4)으로 진행한다. 스탭(S3)에서는 전자밸브(37b,38b)를 ON하고, 스탭(S4)에서는 전자밸브(37b,38b)를 OFF한다. 이와 같이 구성된 본 실시예의 작용에 관하여 설명한다.The rotation speed sensor 20 constitutes a rotation speed detection means, and is connected to the inlet port of the control unit 39 to determine the engine speed with the first maximum value NE according to a program described later. The solenoid valves 37b and 38b are connected to the output port of the control unit 39. When the engine rotational speed exceeds the first maximum value NE, the positron valves 37b and 38b are excited to form a subsequent angle. Pressure oil is supplied to the actuators 37a and 38a. That is, referring to FIG. 13, the step S1 reads the engine speed No based on the signal from the speed sensor 20, and the step S2 reads in advance the engine speed No and the engine speed No in advance. The magnitude of the engine rotation speed stored in the ROM is determined with the first maximum value NE (maximum rotation speed suitable for low load operation of the engine). If the current engine speed No exceeds NE (No> NE), the flow advances to the step S3, and NE or less (No

NE), the processing proceeds to step S4. In step S3, the solenoid valves 37b and 38b are turned on, and in step S4, the solenoid valves 37b and 38b are turned off. The operation of this embodiment configured as described above will be described.

(1) When the engine speed exceeds the first maximum value NE suitable for low load operation, the same control as in the embodiment described with reference to FIGS. 1 to 10 is performed. That is, as shown in the N-Q diagram of FIG. 14, the pump discharge amount Q increases in proportion to the engine speed N. As shown in FIG. The P-Q diagram when the engine speed is NE is as shown by the dashed-dotted line E in FIG.

(2) When the engine speed exceeds the first maximum value suitable for low load operation, if the engine speed exceeds the first maximum value NE by operation of the engine control lever 13f (see FIG. 3), The valve 37b is excited so that the pressure oil with the pressure difference before and after the throttle 36 is respectively introduced into the two inlet ports of the pump maximum tilt angle control actuator 37a. Since the pressure difference before and after the throttle 36 can be expressed as a function of the discharge amount of the fixed displacement type hydraulic pump 31, that is, the engine speed, the engine speed is changed from the first maximum value NE to the second maximum value NP. In between, the extrusion volume is controlled so as to continuously decrease with the engine speed between qE and qP (<qE). In this case, the pump discharge amount is constant in a region where the engine speed is larger than NE as shown in the NQ diagram of FIG. 14 by appropriately determining the strength of the spring 37d and the throttle amount of the throttle 36 in the actuator 37a. . The P-Q diagram when the engine speed is NP is as shown by the solid line P in FIG.

Thus, in this embodiment, the same effect as that of the embodiment of FIGS. 1 to 10 can be obtained. In the present embodiment, the maximum extrusion volume is qE in the low horsepower area below the first maximum value NE suitable for low load operation, and the load of the hydraulic motor 11 in the high horsepower area exceeding NE. The engine rotational speed was increased with pressure, and the maximum tilt angle of the pump was reduced to continuously reduce the maximum extrusion volume from qE as the engine speed was increased. Therefore, when the engine speed exceeds NE, the engine speed is increased. The maximum value of the rotational speed and the maximum value of the extrusion volume can be changed drastically, so that the operability is improved and the burden on the device is also improved.

Example 4

A fourth embodiment will be described with reference to FIG.

In this embodiment, the pressure of the forward port of the hydraulic motor 11 is detected by the pressure sensor 40, and the output from the pressure sensor 40 in the area where the engine speed exceeds the first maximum value NE. The engine speed is controlled in accordance with the voltage, and the other configuration is the same as in the third embodiment.

That is, in the maximum rotation speed changing means 41, the rotation angle of the lever 13a (see FIG. 3) is controlled using, for example, the linear solenoid device 41a instead of the hydraulic cylinder 38a. The output voltage of the pressure sensor 40 is input to the control unit 42, and the control unit 42 outputs the corresponding signal to the linear solenoid 41a, thereby controlling the maximum value of the engine speed.

In this embodiment, since the output voltage of the pressure sensor 40 is first input to the control unit 42 and the signal to the linear solenoid 41a is obtained based on the input voltage, the forward side port of the hydraulic motor 11 When the pressure fluctuates very much, the maximum value of the engine speed can be prevented from fluctuating according to the fluctuation, which is more preferable.

Example 5

A fifth embodiment will be described with reference to FIG.

In this embodiment, the present invention is applied to an excavation circuit, and the maximum value of the engine speed is controlled according to the pressure of the input / output port of the drilling cylinder in the region where the engine speed exceeds NE.

That is, the excavation cylinder 43 is connected to the control valve 30, and the input / output port of the cylinder 43 is connected to the solenoid valve 38b via the shuttle valve 44.

In addition, the control valve 30 is controlled by the excavating pilot valve 45 which is supplied with a supply pressure from the fixed displacement hydraulic pump 31. Other configurations are the same as those shown in FIG.

Also in this embodiment, the maximum rotation speed changing means 38 and the maximum extrusion capacity changing means 37 are not operated in the region where the engine rotation speed is equal to or less than NE, and the engine rotation speed is set to the engine control lever 13f provided in the driver's seat. And the maximum warp angle maximum extrusion volume of the hydraulic pump 14 is maintained at qE, so that the NQ diagram is as shown in FIG. The P-Q diagram at the rotational speed NE is as shown by the dashed-dotted line E in FIG.

On the other hand, in the region where the engine speed exceeds NE, the maximum speed change means 38 and the maximum extrusion volume change means 37 operate, so that the maximum input / output port pressure of the drilling cylinder 43 is increased. It is controlled to increase as it increases, and the maximum extrusion volume of the hydraulic pump 14 is also controlled to decrease as the discharge amount of the hydraulic pump 31, that is, the engine speed, increases. At this time, as described above, the maximum extrusion volume is controlled so that the discharge amount of the hydraulic pump 14 is constant.

In this embodiment, the same effects as those in the second embodiment are obtained, and the use of medium excavation is automatically divided into low excavation in the area where the engine speed exceeds the first maximum value NE suitable for low load operation. Can be. The engine and pump absorption horsepower according to the load can be obtained, thereby providing a hydraulic excavator control system which is extremely excellent in terms of fuel efficiency, noise and operability. As in the fourth embodiment, the pressure of the input / output port of the excavation cylinder 43 may be detected by a pressure sensor.

Example 6

NE)이면 스탭(S₄)으로 진행된다. 스탭(S₃)에서는 전자밸브(37b)를 ON하고 스탭(S₄)에서는 전자밸브(37b)를 OFF한다.17 shows a sixth embodiment of the present invention, in which the control of the engine speed when the engine speed exceeds the first maximum value NE is performed by the means 38 and 41 of the embodiments 3 to 5; The engine rotation speed is controlled as it is by the rotation speed control means 13 as it does for the control of NE or less, without providing the same special change means, and the other structure is substantially the same as that of Examples 3-5. That is, the rotation speed sensor 20 is connected to the input port of the control unit indicated by the sign 47, and the solenoid valve 37b is connected to the output port. In the ROM in the control unit 47, a program as shown in FIG. 18 is stored in advance, and the solenoid valve 37b is turned on and off in accordance with the engine speed. That is, referring to FIG. 18, the step S ₁ reads the engine speed No based on a signal from the rotation speed sensor 20, and the step S ₂ reads the engine speed No. And the magnitude of the first maximum value NE of the engine speed stored in the ROM in advance are determined. If the current engine speed No exceeds the first maximum value NE (No> NE), the process proceeds to the step S ₃ , and NE or less (No

If NE) and proceeds to the staff (S _4). In step S ₃ , the solenoid valve 37b is turned on, and in step S ₄ , the solenoid valve 37b is turned off.

When the engine speed is less than or equal to the first maximum value NE suitable for low load operation, the maximum extrusion volume is set to qE and the engine speed is set to the engine of the driver's seat. The value corresponds to the operation amount of the control lever 13f. When the engine speed exceeds the first maximum value NE suitable for low load operation, the solenoid valve 37b is excited and the engine speed is changed from the first maximum value NE to the second maximum as in the third to fifth embodiments. Between the maximum value NP, the maximum extrusion volume is controlled to continuously decrease with the engine speed from qE to qP. On the other hand, as shown in the N-Q diagram of FIG. 14, pump discharge becomes constant in the area | region where engine speed is larger than NE.

In this embodiment, since the control lever 13f is controlled by the operation of the entire range of the engine speed, the structure is simplified and the operability is greatly improved. In the above third to sixth embodiments, the pressure of the hydraulic circuit of the working actuators 11 and 33 is not used to control the maximum extrusion volume of the hydraulic pump, but the engines of the third to fifth embodiments are described. As used to control the maximum rotational speed, the pressure of the hydraulic circuit can also be used to control the maximum extrusion volume of the hydraulic pump. In addition, although the pressure oil between the hydraulic motor 11 or the hydraulic cylinder 43 and the control valve 30 was taken out as the pressure of the hydraulic circuit, the control valve 30 and the hydraulic pump as shown by the dashed-dotted line in FIG. Similarly, even if the pressure sensor 46 is connected to (14) to detect the discharge pressure of the hydraulic pump, a signal that increases in proportion to the load of the hydraulic actuators 11 and 43 can be obtained. In addition, the detection of the load of the hydraulic actuators 11 and 43 is not limited to the detection of pressure, and the difference between the rotational speed indicated by the control lever of the engine and the actual rotational speed, that is, the rotational deviation may be detected. In addition, a strain gauge may be attached to the rotating shaft of the hydraulic motor to actually detect the load. In the fourth embodiment, the electronic actuator used for the control of the maximum rotational speed may be used for the control of the maximum extrusion volume of the hydraulic pump.

[Examples 7 to 9]

Next, Examples 7 to 9 of the present invention will be described with reference to FIGS. 19 to 26. FIG. In the drawings, the same members are denoted by the same reference numerals in the embodiments and the embodiments 7 to 9 described so far.

In the seventh to ninth embodiments, the control means 53, 56 respond to the operation mode information from the information providing means 25, 24, 55, and when the information indicates the low load operation, When the information indicates high load operation in the first combination where the maximum extrusion volume takes the second maximum value qE and the rotation speed of the engine 12 is small, the maximum extrusion volume of the hydraulic pump is the first. The rotation speed changing means 52 and the maximum extrusion volume changing means 19 are controlled so that the hydraulic pump and the engine 12 are controlled in the second combination which takes the maximum value qp and becomes the rotation speed of the engine 12 having a large rotation speed. It differs from the previous embodiment in that it is controlled.

Example 7

19 shows a seventh embodiment of the present invention, wherein the discharge port of the variable displacement hydraulic pump 14 driven by the engine 12 constituting the prime mover is a traveling hydraulic motor and an excavation via the control valve unit 16. It is connected to the actuator 50 containing the molten cylinder (hydraulic cylinder 5-7 of FIG. 1), and a turning motor. The control valve 16 is switched and controlled by an operation lever (not shown). The extrusion volume of the variable displacement hydraulic pump 14 is controlled in accordance with the circuit pressure by the pump regulator 15 and its maximum extrusion volume is varied by the maximum extrusion volume changing means 19. The changing means 19 has a hydraulic actuator 19a, and by expansion and contraction, the maximum extrusion volume per one revolution of the pump is switched and controlled in two stages. This hydraulic actuator 19a is connected to the pressure source 22 and the tank 23 via a solenoid valve.

The rotational speed of the engine 12 is controlled by the rotational speed control means 51 including a control lever 51a (see FIG. 20), and the rotational speed control means 51 is provided with any rotational speed controlled thereby. Regardless, the rotation speed change means 52 which can change the rotation speed again by a predetermined amount and obtain a large rotation speed and a small rotation speed is provided in connection with it.

In detail, the rotation speed changing means 52 is an intermediate lever between the engine control lever 51a installed in the driver's seat and the speed control throttle lever 51b of the engine 12, as shown in FIGS. 20A to 20C. It is comprised integrally with 51c). Moreover, the rotation speed control means 51 is comprised by the engine control lever 51a, the governing throttle lever 51b, and the intermediate levers 51c and 51d. Referring to FIG. 20A, the engine control lever 51a is supported by a control box 53 in the driver's seat, and is connected to one end of the first intermediate lever 51c supported by a predetermined portion of the vehicle. It is connected via a pushple cable 51e. The 1st intermediate lever 51c is formed in substantially "A" shape, and the hydraulic cylinder 52a of the rotation speed change means 52 is fixed to the other end. The second intermediate lever 51d is coaxially axially coaxially with the first intermediate lever 51c, and the second intermediate lever 51d is rotated by the first intermediate lever 51c via the hydraulic cylinder 52a. Is passed. The second intermediate lever 51d is connected via a pushple cable 51f of the governing throttle lever 51b. The hydraulic cylinder 52a is connected to the hydraulic pressure source 22 and the tank 23 via the solenoid valve 18b.

FIG. 20A shows a case where the engine control lever 51a is in the OFF position and the hydraulic cylinder 52a is reduced, at which time the engine 12 is stopped. Even if the hydraulic cylinder 52a is extended, the second intermediate lever 51d does not rotate. FIG. 20B shows a case where the engine control lever 51a is operated to the maximum position and the hydraulic cylinder 52a is reduced, at which time the engine 12 rotates to the first maximum value NE. FIG. 20C shows a case where the hydraulic cylinder 52a is extended from the state of FIG. 20B, and the second intermediate lever 51d is rotated by the amount of the hydraulic cylinder 52a extended so that the engine reaches the second maximum value NP. It rotates.

With reference to FIG. 21, the relationship between the operation amount of the engine control lever 51a, the engine speed, and the discharge amount of a hydraulic pump is explained in full detail. In the economic mode in which the hydraulic cylinder 52a is reduced, the engine is determined by setting the engine control lever 51a to the position of &quot; OFF E &quot; When the engine speed at this "OFF E" position is zero, the engine speed is adjusted by operating the engine control lever 51a from the "OFF E" position to the maximum position (see also FIG. 20B). You can control from zero (0) to NE. At this time, if the pump extrusion volume is constant at qE, the hydraulic pump discharge amount can be controlled from zero (0) to Q ₀ as indicated by the dashed-dotted line (E). 20A shows a state in which the engine control lever 51a is in the “OFF P” position. However, as can be seen from FIGS. 20A and 21, when the hydraulic cylinder 52a is reduced, In the range from "OFF E" to "OFF P", the engine control lever 51a becomes inoperative. In the power mode in which the hydraulic cylinder 52a is extended, the prime mover stops when the engine control lever 51a is set to the "OFF P" position in FIG. If the engine speed at the &quot; OFF P &quot; position is zero, the engine speed can be adjusted by operating the engine control lever 51a from the &quot; OFF P &quot; position to the maximum position (see also 20c). It is possible to control from zero (0) to NP. At this time, if the pump extrusion volume is constant at qp, the hydraulic pump discharge amount can be controlled from zero (0) to Q ₀ as indicated by the solid line (P).

In this case, the first maximum value NE of the engine speed is set so that 35 km / h is obtained when driving on the flat road at the required minimum horsepower when the pump tilt angle, that is, the extrusion volume is qE, or when the excavation operation is performed at a desired speed. NE and qE are the maximum rotational speed and the maximum extrusion volume suitable for low load operation. In addition, the second maximum value NP of the engine speed is determined so that 35 km / h can be obtained when driving uphill in a desired gradient with the required minimum horsepower when the pump tilt angle, that is, the extrusion volume is qp. , qp is the maximum rotational speed and maximum extrusion volume suitable for heavy load operation. In Fig. 19, reference numeral 53 denotes a controller composed of, for example, a microcomputer, and a mode switching switch 25 that constitutes a selection means is connected to the pressure port.

The mode switching switch 25 is a switch that can be switched between the power mode position P and the economic mode position E, for example, and a toggle switch can be used. The solenoid valve 19c connected to the hydraulic cylinder 19a for maximum warp angle change and the solenoid valve 18b connected to the engine speed change hydraulic cylinder 52a are connected to the output port of the controller 53. have. The solenoid valve 18b and the solenoid valve 19c respond to the switching position of the mode switching switch 25 described above, and the solenoid valves 18b and 19c when the mode switching switch 25 is switched to the power mode position. Is energized and the solenoid valves 18b and 19c are demagnetized when they are cut to the economic mode position.

The operation of this embodiment configured as described above will be described below.

(1) Power mode operation

When the mode switching switch 25 is switched to the power mode position, the solenoid valve 19c is excited and the hydraulic cylinder 19a is connected to the pressure source 22, whereby the maximum extrusion volume changing means 19 shown in FIG. The hydraulic cylinder 19a is operated to set the maximum extrusion volume to qp. At this time, since the solenoid valve 18b of the engine speed change means 52 is also excited and the hydraulic cylinder 52a is extended, when the engine control lever 51a of the driver's seat is pulled to the maximum, as shown in FIG. The engine speed can be increased to the second maximum value NP via the intermediate lever 51d. Therefore, as long as the maximum extrusion volume of the hydraulic pump 14 in the low pressure region (less than the pressure P ₂ : see FIG. 23) is qp, it is proportional to the increase in the engine speed as indicated by the solid line P in FIG. 22. As a result, the pump discharge amount increases, and the maximum discharge amount Q ₀ is obtained at the second maximum value NP of the engine maximum rotational speed. In this case, the PQ diagram of the pump at the engine speed NP is as shown by the solid line P in FIG.

(2) Economic mode operation

When the mode switching switch 25 is switched to the economic mode position, the solenoid valve 19c is demagnetized and the hydraulic cylinder 19a is connected to the tank 23, whereby the maximum extrusion volume is changed to qE (> qp). . At this time, since the solenoid valve 18b is demagnetized and the hydraulic cylinder 52a is reduced, even if the engine control lever 51a of the driver's seat is pulled to the maximum, as shown in FIG. 20 (b), the second intermediate lever 51d is shown. ) Rotates the hydraulic cylinder 52a to the maximum, but as shown in FIG. 20B, the rotation of the second intermediate lever 51d is as small as the reduction of the hydraulic cylinder 52a. It is limited to the maximum value (<NP).

Therefore, as long as the maximum extrusion volume of the hydraulic pump 14 is qE in the low pressure range (below pressure P ₁ : see FIG. 23), the engine speed is increased as indicated by the dashed-dotted line E in FIG. The pump discharge amount increases in proportion to and the maximum discharge amount Q ₀ is obtained when the engine speed reaches the first maximum value NE. In this case, the PQ diagram of the pump at the engine speed NE is as shown by the dashed-dotted line E in FIG. Moreover, the curve shown by the broken line in FIG. 23 shows the PQ diagram when the engine speed rises to 2nd maximum value NP, for example, when switching to the largest extrusion volume qE.

(3) Mode switching operation

When the mode switching switch 25 is switched to the economic mode position during the power mode operation, the solenoid valves 18b and 19c are elemented. As a result, the hydraulic cylinder 19c is reduced so that the maximum extrusion volume of the hydraulic pump 14 is qE. In addition, since the hydraulic cylinder 52a is reduced so that the second intermediate lever 51d follows it and rotates counterclockwise in FIG. 20C, the engine speed decreases by a predetermined value. Therefore, even if the engine rotational speed is in any region, the discharge amount of the hydraulic pump is almost constant and shifts from the power mode to the economic mode on the N-Q diagram according to the arrow A in FIG. In contrast to this, switching from the economic mode to the power mode is performed in reverse, so that the discharge amount of the hydraulic pump is almost constant in the entire engine speed range from the economic mode to the power mode on the NQ diagram according to the arrow B of FIG. Is implemented.

까지 저하해버려 소정의 속도를 얻을 수가 없다.In the present embodiment, in the economic mode, the maximum extrusion volume of the pump is increased to qE (> qp), the engine speed is limited to the first maximum value NE (<NP), and the maximum pumping amount is set to Q ₀ . By this, the working speed including the running speed in the economic mode and the power mode at the pump maximum discharge amount is made the same. Therefore, with reference to FIG. 9 mentioned above, for example, required horsepower PS ₂ can be obtained at engine speed NE ₁ , fuel consumption can be reduced to g ₂ , and noise can also be reduced. On the other hand, considering that the pump discharge volume can reach a maximum speed of 35 km / h at Q ₀ , as shown in FIG. 23, the pump discharge pressure is required to be P ₁ (for example, when driving on a flat road in economic mode). pressure) until 35㎞ / h to travel to, but if the pump discharge pressure, such as when climbing the head exceeds P _1, but the running can roneun 35㎞ / h, the power mode, the pump discharge pressure, for P ₂ (for example, It is possible to drive up to 35 km / h up to the pressure required for driving on a hill at an angle θ. Therefore, in the conventional pump, when the engine speed is lowered from N ₂ to NE ₁ (see FIG. 9) as in the present embodiment, when the pump absorption horsepower is lowered to thereby obtain fuel economy, the pump maximum extrusion volume is constant. The diagram is like the dashed line in FIG.

It is lowered until it is impossible to obtain a predetermined speed.

Example 8

Embodiment 8 of the present invention will be described with reference to FIG. In the control system of this embodiment, the load detection sensor 54 and the automatic control selection switch 55 are provided again with respect to the configuration of the seventh embodiment, and these load detection sensors 54 are provided at the input port of the controller 56. And automatic control selection switch 55 are connected. The load detection sensor 54 detects the load of the actuator 50, and in the illustrated embodiment, is configured by a pressure detector that detects the pressure of the hydraulic circuit between the control valve 16 and the actuator 50. . In addition, as in the case of the embodiment described above, the load sensor may be used to detect an engine speed deviation, or may be a strain gauge to detect a mechanical load. In the case of detecting the pressure, the pressure in the pipeline between the hydraulic pump 14 and the control valve 16 may be detected. The automatic control selection switch 55 automatically switches according to the manual position at which the switching between the power mode operation and the economic mode operation is performed by the manual switching of the mode switching switch 25 and the load detected by the sensor 54. Switch to position. The controller 56 controls the switching of the solenoid valves 23 and 27 according to the program shown in FIG. In other words, the method according to claim 25 the staff ₍₁ S) sensor 54, a switch in dokip and procedure signals of the switches _{(25,55) (S 2) (} 55) in it is determined whether automatic or manual position location . If the manual positioning staff (S ₃₎ switch 25 in the position it is determined whether the power mode if the economy mode position.

When the power-mode position to ON (woman) with the solenoid-operated valve (18b, 19c) in the step (S _4). When the economy mode is OFF position (element) with the solenoid-operated valve (18b, 19c) in the step (S _5). On the other hand, the switch 55 is equal automatic position when the step (S ₆₎ in, detecting the difference is more than determined, and a predetermined value whether or not the applied predetermined value or higher staff (S ₄₎ under progress, and a predetermined value to the step (S ₅₎ Proceed to

According to this embodiment, the operation mode is automatically switched by selecting the automatic control position of the switch 55 with respect to the advantages of the seventh embodiment, so that work can be performed in the most advantageous state regardless of the skill of the driver.

Example 9

A ninth embodiment of the present invention will be described with reference to FIG. The controller of the control system of this embodiment is adapted to control the solenoid valves 18b and 19c according to the program shown in FIG.

In the automatic mode switching operation by the program shown in FIG. 25 according to the eighth embodiment, there is a fear that hunting occurs when the load of the actuator fluctuates around a predetermined value.

Figure 26 is a program to prevent such hunting. According to the program shown in FIG. 26, when the solenoid valves 18b and 19c are switched and controlled according to the load change of the actuator, the state is maintained irrespective of the load change until a predetermined time elapses, thereby preventing hunting. do. That is, if automatic control is selected in the step S ₂ , it is determined in step S _{7 whether} the selection switch 55 and the time t after the switching have exceeded the predetermined time Ta and have been determined to have exceeded. At this time, the process proceeds to step S ₈ , where it is determined whether the detection load is greater than or equal to the predetermined value, and if less than or equal to the predetermined value, the process proceeds to step S ₉ , and if it is greater than or equal to the predetermined value, the processing proceeds to step S ₁₀ . In the steps S ₉ and S ₁₀ , it is determined whether or not the flag is set. When it is determined that the flag is not set, the timer counting the time t in the steps S ₁₁ and S ₁₂ is cleared. Next, a flag is set in the step S ₁₃ and a flag is cleared in the step S _14. On the other hand, when it is determined that the flag is set in the steps S ₉ and S ₁₀ , the direct step S ₁₃ , proceeds to S _14, respectively), followed by being OFF both the step (S ₁₅₎ solenoid valves (18b, 19c) in, step (is oN with S ₁₆₎ controls the solenoid valve in the hydraulic construction machine siseutemga.

In this way, by judging the flag set, it is checked whether or not the load of the actuator has fluctuated before and after the predetermined value, and when it changes, the timer count is cleared and no signal is sent to the solenoid valve control loop until the predetermined time has elapsed. Since a return is made, even if there is a load change, the previous operation mode can be maintained until a predetermined time has elapsed.

In this embodiment, the engine speed is changed by the engine speed change means 52 so that the engine speed can also be changed between a large value and a small value at the same time as the maximum extrusion container is changed in the entire range of the engine speed. Nevertheless, the pump discharge amount never changes.

In the above description, qp, NP, qE, and NE are set so that the pump maximum discharge amount Q ₀ (= qp x NP = qE x NE) in each mode is the same. However, if both are substantially the same, they may not be the same. For example, the maximum traveling speed in each mode may be different from 30 km / h to 35 km / h.

In addition, in the above description, although the change of the maximum extrusion volume and engine speed of the pump was controlled by the hydraulic cylinder, you may use an electronic thing. In addition, by using a linear solenoid or by using a plurality of hydraulic cylinders, the maximum tilt angle can be set in three or more steps or continuously, and the increase or decrease of the engine speed can be controlled accordingly. By setting an engine and a hydraulic device, further fuel economy can be improved. The present invention can also be applied to the case where the oil pump 14 is driven by an electric motor instead of an engine.

In addition, the engine speed may be increased or decreased by increasing or decreasing the fuel injection amount using an electronically controlled governor. In this case, the hydraulic cylinder 52a and the second intermediate lever 51d are unnecessary. Again, the wheel hydraulic excavator has been described above, but it can be applied to other construction machinery with large load fluctuations.

In addition, in the above embodiment, the predetermined amount of the engine speed changed by the rotation speed changing means 52 is set to approximately the same constant value as the first maximum value NE and the second maximum value NP. The smaller the smaller the predetermined amount is, the more effectively the variation of the pump discharge amount can be eliminated even when the rotational speed changes in the rotational speed below the first maximum value.

Claims (17)

Controls the prime mover 12, rotational speed control means 13 and 51 for controlling the rotational speed of the prime mover, at least one variable displacement hydraulic pump 14 driven by the dual prime mover, and the extrusion volume of the hydraulic pump. The maximum volume of the prime mover 12 in relation to the extrusion volume control means 15, at least one actuator 11, 17, 43, 50 driven by the pressure oil discharged from the hydraulic pump, and the rotation speed control means. Maximum rotation speed changing means (18,38,41,13,52) for changing the rotation speed between at least the first maximum value (NE) and the second maximum value (NP) larger than that, and the extrusion volume control means. Related to the maximum extrusion volume changing means (19, 37) for changing the maximum extrusion volume of the hydraulic pump between at least the first maximum value qp and the second maximum value qE larger than that; Information providing means (20, 25, 60, 36, 40, 44, 54, 55) for providing information and providing information By controlling the maximum rotation speed changing means and the maximum extrusion volume changing means by the output signal from the stage, the control of the hydraulic construction machine which can obtain the maximum rotation speed and the maximum extrusion volume suitable for the operation mode indicated by the output signal. In the system, in response to an output signal of the information providing means 20, 25, 60, 36, 40, 44, 54, 55, the extrusion volume and the extrusion volume are always at the same time when the maximum extrusion volume of the hydraulic pump 14 is changed. Controlling the maximum rotational speed changing means 18,38,41,13,52 and the maximum extrusion volume changing means 19,37 so as to change at least the maximum rotational speed of the prime mover 12 so that the product of the rotational speed is approximately constant. And control means (21, 39, 42, 47, 53, 56) for preventing the discharge amount of the hydraulic pump from substantially changing when the maximum extrusion volume of the hydraulic pump is changed. Control System. 2. The apparatus according to claim 1, wherein said information providing means includes a rotation speed detecting means (20) for detecting the rotation speed of said prime mover (12), and said maximum rotation speed changing means (18,38,41,13) includes: And configured to change the rotation speed again when the rotation speed of the prime mover controlled by the rotation speed control means 13 exceeds the first maximum value NE, and the control means 21, 39, 42, In response to the output signal of the rotation speed detecting means, the maximum extrusion volume of the hydraulic pump 14 is reduced when the rotation speed of the prime mover 12 is at the first maximum value NE and smaller than that. Taking the second maximum value qE, if the rotational speed of the prime mover 12 exceeds the first maximum value, the maximum extrusion volume of the hydraulic pump is reduced and the maximum rotational speed of the prime mover 12 is synchronized. The maximum rotational speed changing means (18,38, 41, 13) and the maximum extrusion volume changing means (to increase the 19,37 control system of a hydraulic construction machine configured to control. 3. The control means (21) according to claim 2, wherein the control means (21) changes the maximum extrusion volume of the hydraulic pump (14) discontinuously when the number of revolutions of the prime mover (12) exceeds the first maximum value (NE). The maximum speed qp of the prime mover 12 is changed to the second maximum value NP by the maximum speed change means 18, while changing the first maximum value qp by the means 19. Control system of hydraulic construction machinery, configured to change. 3. The control unit (39, 42, 47) according to claim 2, wherein the control means (39, 42, 47) continuously the maximum extrusion volume of the hydraulic pump 14 when the number of revolutions of the prime mover 12 exceeds the first maximum value (NE) The maximum rotational speed of the prime mover 12 is changed by the maximum rotational speed changing means 38, 41, and 13, while the maximum extrusion volume changing means 37 is changed to the first maximum value qp. A control system for a hydraulic construction machine configured to change to a second maximum value NP. 3. The control means according to claim 2, wherein said information providing means further includes operation mode selecting means (25) for selecting which of the operation modes of said actuators (11, 17) to be a power mode and an economic mode. 21, in response to the output signal of this driving mode selecting means, the rotation speed of the prime mover 12 exceeds the first maximum value NE and the output signal of the driving mode selecting means indicates the power mode. A control system for a hydraulic construction machine configured to control the maximum extrusion volume changing means (19) and the maximum rotation speed changing means (18) so as to change the maximum extrusion volume and the maximum rotational speed only when there is. In the hydraulic construction machine according to claim 4, wherein the rotation speed control means (13) includes an engine control lever (13f) installed in the driver's seat, wherein the maximum speed change means includes the rotation speed control means, and the control means ( The information providing means 47 changes the maximum rotation speed by operating the engine control lever of the rotation speed control means again when the rotation speed of the prime mover 12 exceeds the first maximum value NE. And the maximum extrusion volume changing means (37) in response to the output signal of (36), thereby continuously changing the maximum extrusion volume and the maximum rotational speed. 7. A control system for a hydraulic construction machine according to claim 6, wherein said information providing means is a throttle (36) for generating a differential pressure that increases with an increase in the number of revolutions of said prime mover (12). 5. The control means according to claim 4, wherein the information providing means includes load detecting means (60, 40, 44, 46) for detecting a load of the actuators (11, 43) and outputting a load signal corresponding thereto. 39 and 42 indicate the maximum rotation speed changing means 38 and 41 in response to an output signal of the load detecting means when the rotation speed of the prime mover 12 exceeds the first maximum value NE; Controlling the maximum extrusion volume changing means (37), thereby continuously changing the maximum extrusion volume and the maximum rotational speed. 5. The load detecting means (60, 40, 44, 46) according to claim 4, wherein the information providing means again detects the load of the actuators (11, 43) and outputs a load signal corresponding thereto, and the prime mover (12). And a throttle 36 for generating a differential pressure that increases with an increase in the number of revolutions of the motor, and the control means 39 and 42 may have exceeded the first maximum value NE. At this time, while controlling the maximum rotational speed changing means 38, 41 in response to the output signal of the load detecting means, the maximum extrusion volume changing means 37 is controlled in response to the differential pressure of the throttle, whereby Control system for hydraulic construction machines designed to continuously change extrusion volume and maximum speed. 10. A control system for a hydraulic construction machine according to claim 9, wherein the load detecting means is pressure detecting means (60, 40, 44, 46) for detecting the oil pressure of the driving hydraulic circuit of the actuator (11, 43). The rotational speed according to claim 1, wherein the maximum rotation speed changing means changes the rotation speed again by a predetermined amount regardless of the rotation speed of the prime mover 12 controlled by the rotation speed control means (51). Rotation speed changing means 52, which makes it possible to obtain a number and a small rotation speed, and the control means 53, 56 transmits the information in response to the operation mode information from the information providing means 25, 54, 55. When the low load operation is indicated, the information is obtained by a first combination in which the maximum extrusion volume of the hydraulic pump 14 takes the second maximum value NE, and the rotation speed of the prime mover 12 is the small rotation speed. Is the second combination where the maximum extrusion volume of the hydraulic pump takes the first maximum value qp, and the rotation speed of the prime mover 12 is the larger rotation speed when the high load operation is indicated. 12 to be controlled Group speed changing means (52) and the maximum extrusion volume of the hydraulic construction machine control system adapted to control the changing means (19). 12. The prime mover according to claim 11, wherein said rotation speed changing means (52) is said predetermined amount by approximately equal to a difference between a first maximum value (NE) and a second maximum value (NP) of the rotational speed of said prime mover. A control system for a hydraulic construction machine adapted to change the number of revolutions of (12). 12. The control means (53) according to claim 11, wherein said information providing means includes an operation mode selecting means (25) for selecting whether the operation mode of said actuator (50) is a power mode or an economic mode. In response to the output signal of the operation mode selecting means, the output signal is judged to be low when the economic mode is indicative, and is judged to be high load when the power mode is indicative, and control is performed in a corresponding combination. Control system of hydraulic construction machinery. 2. The apparatus according to claim 1, wherein the information providing means includes load detecting means (54) for detecting a load of the actuator (50) and outputting a load signal corresponding to the negative term. In response to the output signal of the cupping detecting means, when the detected load is smaller than the predetermined value, it is determined that it is a low load operation; when it is larger than that, it is determined that it is a high load operation, and the hydraulic construction is configured to perform control in a corresponding combination. Machine control system. 12. The apparatus according to claim 11, wherein the information providing means detects the load of the actuator 50 and outputs a load signal corresponding to the load and the operation mode of the actuator in power mode and economy mode. And automatic control selecting means 55 for instructing which mode to select the operation mode selecting means 25 and the braking control, wherein the control means 56 includes these load detecting means and operation mode selecting means. And when the automatic control is selected by the automatic control selecting means, whether the low load operation or the high load operation is determined by the output signal of the load detecting means, and when the automatic control is not selected, by the output signal of the operation mode selecting means. A control system for a hydraulic construction machine, which determines whether it is a low load operation or a high load operation, and controls each of the corresponding combinations. The control system for a hydraulic construction machine according to claim 14 or 15, wherein the load detecting means is pressure detecting means (54) for detecting a driving hydraulic circuit of the actuator (50). 16. The method according to claim 14 or 15, wherein when the control means 56 controls the output signal of the load detection means 54, the first combination and the second combination are changed. A control system for a hydraulic construction machine configured to maintain a changed new combination until a predetermined time Ta after the change.

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